Introduction

In the world of motion control applications, voltage efficiency helps increasing the overall performance of the motor control allowing higher speeds to be reached. The Micro 4804 family of miniature drives stand out by achieving an impressive 91% minimum voltage efficiency at 100 kHz PWM frequency, making them the perfect choice for compact, high-precision systems that demand both power and reliability.

Understanding PWM in Motor Control

PWM (Pulse Width Modulation) is the most used method for controlling power delivery in power electronics and motor control systems. PWM works by rapidly switching the drive outputs on and off, varying the “on” time (or duty cycle) to control the voltage delivered to the load. The longer the “on” time relative to the “off” time, the more power is delivered to the motor.

Why PWM?

• It converts DC voltage into a near-sinusoidal waveform, allowing for vector control.
• It enables precise speed control with minimal power loss.
• It offers efficient torque control, providing smooth operation even under varying loads.

Impact of PWM Frequency on motor voltage

The direct effect of the PWM frequency is found in the power losses and heating of the system. On one side, the frequency dictates the switching loses in the drive (each time a transistor is switched on or off a small part of the energy transferred is lost as heat and if these operations happen at a faster rate – higher frequency – the transistor will start to heat up) while on the other side it helps alleviate the current ripple in the motor (the higher the frequency, the less the current will deviate from the desired average value, being subjected to smaller periods of time to a constant voltage).

In the same time, there’s also an indirect effect of the PWM frequency – the higher the frequency, the lower the available voltage for the motor control. This happens due to the fact that our drive needs a small amount of time to measure the current in the motor. For a correct measurement, during this time it’s not allowed to have any transitions and this means that there’s a minimum pulse which must be implemented for the correct operation of the drive.

Current Measurement and Micro 4804 Optimizations

Current measurement is essential for providing accurate and efficient system performance. If current measurements aren’t properly synchronized with the PWM signal, the readings might not reflect the true current flowing through the system, leading to control errors and reduced efficiency. By aligning these processes, the Micro 4804 overcomes the challenges of switching losses and efficiency at high frequencies through a blend of advanced hardware and software optimizations:

• High-performance transistors with minimal switching losses.
• Optimized software algorithms that reduce the minimum pulse time required for current measurement.
• Harmonic injection techniques (e.g., third-harmonic injection) to further boost the effective voltage.

At 100 kHz PWM frequency, the Micro 4804 family achieves an impressive 91% voltage efficiency which goes only up, reaching 98.3% when the drive is used with the default 20kHz PWM signal.

Optimizing Performance for Motors with Low Electrical Time Constant

Motors with low electrical time constants require high-frequency PWM to maintain stable and precise current control. The Micro 4804 is designed to meet the needs of these demanding systems, offering:

• High PWM frequency capability for reduced ripple and enhanced current response.
• Advanced control algorithms that improve system stability.
• Dual-scale current sensing, providing better measurement resolution for small motors, while still scaling up for big motors as well.

Additional Features of the Micro 4804

Beyond its outstanding voltage efficiency, the Micro 4804 offers a range of features that make it ideal for modern motion control applications:

• Ultra-compact size for space-constrained designs.
• Integrated motion control, reducing the need for external controllers.
• Advanced communication interfaces, including CAN and EtherCAT.
• Flexible dual-loop feedback support for precise position and velocity control using absolute encoders.
• Two Safe Torque-Off (STO) inputs, ensuring compliance with SIL3/Cat3/PLe safety standards.

Conclusion

By combining cutting-edge PWM techniques, precise current measurement, and both hardware and software optimizations, the Micro 4804 delivers exceptional performance in compact, high-demand applications. Whether you’re working in industrial automation, robotics, or precision motion control, this drive offers unmatched efficiency, reliability, and versatility.

Want to learn more about how the Micro 4804 can transform your application? Contact our team today!